Membrane hinge for toilet seat



Oct. 11, 1966 N. L. CARLSON 3,277,500

MEMBRANE HINGE FOR TOILET SEAT Filed Oct. 28, 1963 5 Sheets-Sheet 1 3 INVENTOR.

NORMA/v A. CAALSOM ATTORNEK Oct. 11, 1966 N. L. CARLSON MEMBRANE HINGE FOR TOILET SEAT 5 Sheets-Sheet 2 Filed Oct. 28, 1963 r W raw-x A".

INVENTOR. A/OIPNA/VL. CARL 50M ATTORNEY,

Oct. 11, 1966 N. L. CARLSON MEMBRANE HINGE FOR TOILET SEAT 5 Sheets-Sheet 5 Filed 061;. 28, 1963 [iii 30 T 12 INVENTOR.

25 NORMA/v L. CARL so/v.

ATTORNEY United States Patent Office 3,277,500 Patented Oct. 11, 1966 3,277,500 MEMBRANE HINGE FOR TOILET SEAT Norman L. Carlson, 307 W. Royal Palm Road, Phoenix, Ariz. Filed Oct. 28, 1963, Ser. No. 319,438

2 Claims. (Cl. 4-236) This invention pertains to hinges and more particularly to a membrane hinge for toilet seats.

One of the objects of this invention is to provide a hinge for a toilet seat that is cheaper to manufacture and which can be affixed with less effort to the seat.

It is also an object to provide a hinge for the aforementioned use which effects a considerable saving in material requirements.

Of the many new plastics available in production quantities, polypropylene and polyallomer exhibit natural hinging properties. Flexure causes alignment of the molecular chains in the region of bending. This orientation gives rise to a limited increase of tensile strength and a decrease to the resistance to bending. These characteristics are the inverse exhibited by most materials which suffer adversely under conditions known as fatigue, wherein repeated bending reduces tensile strength and increases rigidity. Although use of the aforementioned plastic materials in the form of a membrane hinge between two relatively rigid members of the same material (injection moulded in one piece with the membrane formed by reducing the cross sectional area in a defined manner) has, or had great novelty, its use as such is now in the public domain.

An object of this invention is to construct a toilet seat hinge made of plastic or other material exhibiting antifatigue properties, such as polypropylene and polyallomer, which employs the membrane principle. The arrangement incorporates many features embodied to overcome the drawbacks inherent in the rigid hinge presently used throughout the country. It separates the supporting and hinging functions thereby relieving the mounting bolt of loading stresses. It encloses and protects the attaching wood screws (if used) to protect them from moisture which leads to corrosion and swelling.

Further features and advantages of this invention will appear from a detailed description of the drawings in which:

FIG. 1 is a plan view showing the hinges incorporating the features of this invention mounted on a toilet seat structure.

FIG. 2 is an enlarged fragmentary sectional view on the line 2--2 of FIG. 1.

FIG. 3 is an enlarged fragmentary sectional view on the line 33 of FIG. 2.

FIG. 4 is an enlarged plan View of one of the membrane hinges.

FIG. 5 is an enlarged sectional view on the line 55 of FIG. 4.

FIG. 6 is a front elevation of the hinge shown in FIG. 4.

FIG. 7 is an enlarged fragmentary sectional view on the line 77 of FIGS. 1 and 4 showing the seat in neutral position in normal use with rear and front bumpers of equal height.

FIG. 8 is an enlarged fragmentary sectional view similar to FIG. 7 but showing the situation with high front bumpers on the seat.

FIG. 9 is an enlarged fragmentary section view similar to FIG. 7 but showing the situation with low or no front bumpers on the seat.

FIG. 10 is a diagrammatic view showing a seat and top in lowered normal and raised positions utilizing a conventional height membrane hinge.

FIG. 11 is a diagrammatic view similar to FIG. 10, but utilizing the lower height membrane hinge shown in the several figures of the drawings.

As an example of one embodiment of this invention, there is shown a set of hinges 10 and 11 attached to the bowl rim 12 by the bolts 13 and nuts 14 inserted in the locating holes 15. Each hinge 10 and 11 is secured to both the top 16 and seat 17 by suitable wood screws 18 or some other equivalent fastener. The hinge axis 19 is offset forwardly of the plane 20 defined by the bolt axes 21 and is lowered to be closely adjacent to the top surface 22 of the bowl rim 12 so as to improve the stability of the top 16 and seat 17 when in the upright position. It should be noted that this typical design does not preclude adaptations or modifications to fulfill specific requirements. For instance, the length and angle of the upper web 23 could be changed to accommodate a different seat configuration as could the thickness of the upper bumper 24 and lower bumper 25. The bolt 13 could be moulded to the hinge and a snap in bowl fastener could be used in place of a bolt, if desired. Modifications to replace the bolt and wood screws with all plastic compression fasteners are definitely contemplated as within the scope of this invention.

The hinging function is obtained by forming two membranes 26 and 27 between the upper web 23, lower web 28 and bowl pad 29 of a single plastic casting of polypropylene, polyallomer or equivalent material, by standard injection moulding techniques. The upper web 23 and lower web 28 to which the top 16 and seat 17 are attached are reduced in thickness to form the membranes 26 and 27 where they join the bowl pad 29. This pad 29 is secured to the bowl rim 12 by the bolt 13. The front edge of the pad provides a stable axis 19 or fulcrum about which the upper web membrane 27 and lower web membrane 26 bend when the top 16 and/ or seat 17 are raised or lowered. The top 16 and seat 17 can be moved together or separately. There are, of course, two such pieces 10 and 11 which must be properly aligned to prevent twisting and stressing the membranes, both pieces sharing the common center of rotation 19. This is accomplished by attaching the upper web 23 and lower web 28 to the lower surfaces 30 and 31 of the seat 17 and top 16. The bowl pads 29 are secured to the rear relatively flat top 32 of the bowl rim 12 by bolts 13 passing through the clearance holes 15 located at 5 /2 inch centers perpendicular to the center line of the bowl.

Instead of the sliding surfaces such as the conventional shaft and journal employed by the rigid hinge, "bending of the membranes 26 and 27 is used to effect rotation. Preferably each membrane may be reinforced at the edges by a rib or bead (not shown) moulded with smooth, curved surfaces to reduce the possibility of failure by tearing since both polypropylene and polyallomer are notch sensitive. Such a bead or rib is standard practice followed by mould designers. The thickness of the membrane is approximately 0.015 inch and that of the bead about 0.05 inch.

Under normal conditions encountered from applied loads, for example, 200 pounds applied vertically on one corner of the seat or top, the membrane hinge relieves the bolt and hinge point of stress by transmitting vertical forces to the bowl rim through the rear bumpers 24 and 33. The supporting function, provided by these rear bumpers 33, is thereby separated from the hinging function of the membrane. This separation of functions is made possible by providing the flexible webs 23 and 28. The thickness of these webs 23 and 28 relative to that of the membranes, is such that normal hinging occurs at the membrane fulcrum 19 but that abnormal bending can occur along the length of the webs. In addition, the

membrane itself has suflicient length to accommodate a certain amount of misalignment, FIGS. 7, 8 and 9.

The neutral position, FIG. 7, shows the pad 29, rear bumper 33, and front bumpers 40 all at design height above a flat, level bowl rim 22, 32. The positive sloping web, FIG. 8, shows conditions when the front bumper 40 is twice the thickness of the rear bumper 33 with the pad and bumpers resting on a flat, level bowl rim 22, 32. The negative sloping web 28, FIG. 9, shows conditions when the front bumper is missing with the pad 29, rear bumper 33, and seat 17, resting on the fiat level bowl rim 22, 32. FIGS. 7, 8 and 9 do not show any bending of the web but this can occur without damage to the hinge.

It will be noted that by use of the above described membrane hinge structure the location of the hinge axis 19 or fulcrum is inch lower and closely adjacent the top surface 32 of the bowl 1w than that found on conventional rigid hinges. The purpose of changing its position is to improve the stability of the seat when it is in the raised position. In most domestic units, the front of the tank 34 is behind the center line 20 of the bowl rim locating holes 15. Assuming the weight and center of gravity of the seat and top remain constant, the moments about the hinge axis or fulcrum increase when the seat is raised the axis or fulcrum is lowered. See FIG. 10. Comparison of FIG. 10 and FIG. 11, showing conditions with two different fulcrum heights (1 inch and A inch) but similar seat, top, and tank dimensions, yields an improvement in upright stability. Obviously, repositioning of the fulcrum in the forward direction has the same effect. However, leaving the fulcrum point 3 inches (1% X A) in front of the tank, where it is located on hinges in present use, permits adequate stability without departing from widely accepted dimensions.

Because the supporting function is provided by the bumpers when in the lowered position with membranes carrying the seat and top weight when raised, the bolts 13 are not subjected to heavy stresses. Their only function is to provide the correct and stable location of the pad, seat and top with respect to the bowl. This fact makes possible and practical the use of snap-in fasteners in lieu of bolts and nuts, if desired.

In the design shown the head 35 of the bolt is shaped to increase the contact pressure at the perimeter of the pad. Although the top of the bowl rim is smooth, it is not necessarily flat. The relatively small area of the pad and the perimeter pressure overcome irregularities and insure a moistureproof seal that can be easily kept clean. The bolt 13 is separate from the pad, in this design, to permit used of a smaller packing carton than if it were permanently attached.

The upper rear bumpers 24 and lower rear bumpers 25 differ only in height, if necessary. Their function is to transmit seat and top loads directly to the bowl rim surface 32. Preferably, they are a moulded extension of the webs 23 and 28 and are used to enclose the wood screw fasteners 18. As mentioned previously, the wood screw fasteners 18 may be replaced with plastic compression fasteners in which case the bumper design would be modified. In its present form for use with conventional wood screws 18 it is comprised of two parts attached by a flexible membrane 36. The walls 37, FIGS. 4, and 6, of the bumper, extended from the Webs 23 and 28, bear the load and are spaced to accommodate the round headed wood screws 18. The plugs 38 which make up the second part of the bumper, are attached to the front wall by the membrane 36. After the wood screw fasteners 18 are driven home, the plugs are folded under and snapped into place. A post 39 in the center of the plug 38 is provided to bear load in conjunction with the walls 37. The plug is designed to provide a moistureproof enclosure for the wood screws 18 when snapped into the bumper walls. It also provides a smooth bottom surface 41 on the bumpers 24 and 25.

The membrane 36 by which the plug is attached to the front wall of the bumper is not used regularly as a hinge. Its primary function is to attach the plug. Used in this context, the membrane not only facilitates assembly, no separate pieces to handle, but also assures that a particular plug is snapped into a specific bumper. This latter fact permits adjustment of individual cavity dimensions to obtain a tight fit between the walls 37 and plugs 38 of each bumper but precludes the necessity of maintaining close dimensional tolerance of non-mating cavities. Provided each plug fits its respective bumper, there can be substantial variations of part dimensions without danger of misfits.

In summary, the distinctive features of this toilet seat hinge are:

(1) Use of a membrane hinging element in place of the sliding surfaces found in a conventional hinge.

(2) Use of rear bumpers as supporting elements.

(3) Enclosure of corrosion vulnerable wood screw fasteners within the bumper.

(4) Use of a membrane indexing element to ensure registration of mating parts and reduce handling time.

(5) Repositioning of the center of rotation to improve stability in upright position.

(6) Separation of hinging and supporting functions to relieve bolt stresses induced by loading.

(7) Reduction of material volume over that required by conventional hinge.

(8) Accommodation of misalignment by flexible members and membranes.

While the apparatus herein disclosed and described constitutes a preferred form of the invention, it is also to be understood that the apparatus is capable of mechanical alteration without departing from the spirit of the invention and that such mechanical arrangement and commercial adaptation as fall within the scope of the appendant claims are intended to be included herein.

Having thus fully set forth and described this inven tion what is claimed and desired to be obtained by United States Letters Patent is:

1. A membrane hinge for a toilet having:

(a) a bowl rim including a flat top surface,

(b) a seat having a lower surface,

(0) and a top having a lower surface,

(d) said membrane hinge comprising in combination a bowl pad adapted to be secured to the fiat top surface of said bowl,

(e) a lower web,

(f) a stretchable membrane hinge having a fixed axis of swing movement pivotally interconnecting the rear edge of said lower web to the front upper edge of said bowl pad,

(g) an upper web,

(h) a second stretchable membrane hinge having an axis of swinging movement in alignment with the pivot axis of said first mentioned membrane hinge pivotally interconnecting the rear edge of said upper web to the front upper edge of said bowl pad adjacent to and axially aligned with said first mentioned membrane hinge,

(i) bumpers formed integral with the outer forward ends of said lower and upper webs closely adjacent the rear ends of said seat and said top,

(j) means for securing the bumper on said lower web to the lower surface of the seat,

(k) and means for securing the bumper on said upper web to the lower surface of the top.

2. A membrane hinge for a toilet having:

(a) a bowl rim including a flat top surface,

(b) a seat having a lower surface,

(0) and a top having a lower surface,

(d) said membrane hinge comprising in combination a bowl pad adapted to be secured to the fiat top surface of said bowl,

(e) a lower web,

(f) a membrane hinge pivotally interconnecting the rear edge of said lower web to the front upper edge of said bowl pad,

(g) an upper web,

(h) a membrane hinge pivotally interconnecting the rear edge of said upper web to the front upper edge of said bowl pad adjacent to an axially aligned with said first mentioned membrane hinge,

(i) bumpers formed integral with the outer forward ends of said lower and upper webs,

(j) mean for securing the bumper on said lower web to the lower surface of the seat,

(k) means for securing the bumper on said upper web to the lower surface of the top,

(1) bumper plugs adapted to cover said means for securing said bumpers to the seat and top including,

(m) a membrane hinge at the forward lower edge of References Cited by the Examiner UNITED STATES PATENTS 3,009,169 11/1961 Bodner 4240 3,075,204 1/1963 Rocker 4236 FOREIGN PATENTS 1,201,033 7/1959 France.

LAVERNE D. GEIGER, Primary Examiner. H. GROSS, Assistant Examiner. 

1. A MEMBRANE HINGE FOR A TOILET HAVING: (A) A BOWL RIM INCLUDING A FLAT TOP SURFACE, (B) A SEAT HAVING A LOWER SURFACE, (C) AND A TOP HAVING A LOWER SURFACE, (D) SAID MEMBRANE HINGE COMPRISING IN COMBINATION A BOWL PAD ADAPTED TO BE SECURED TO THE FLAT TOP SURFACE OF SAID BOWL, (E) A LOWER WEB, (F) A STRETCHABLE MEMBRANE HINGE HAVING A FIXED AXIS OF SWING MOVEMENT PIVOTALLY INTERCONNECTING THE REAR EDGE OF SAID LOWER WEB TO THE FRONT UPPER EDGE OF SAID BOWL PAD, (G) AN UPPER WEB, (H) A SECOND STRETCHABLE MEMBRANE HINGE HAVING AN AXIS OF SWINGING MOVEMENT IN ALIGNMENT WITH THE PIVOT AXIS OF SAID FIRST MENTIONED MEMBRANE HINGE PIVOTALLY INTERCONNECTING THE REAR EDGE OF SAID UPPER WEB TO THE FRONT UPPER EDGE OF SAID BOWL PAD ADJACENT TO AND AXIALLY ALIGNED WITH SAID FIRST MENTIONED MEMBRANE HINGE, 